Method of manufacturing a timber composite, the timber composite obtained and decorative panels comprising such timber composite

ABSTRACT

A method of manufacturing a timber composite (7) is disclosed. The method comprises the steps of applying adhesive to one or more timber layers (23-226), applying pressure to the one or more timber layers, and heating the timber layers. The adhesive penetrates into the one or more timber layers and cures to form the timber composite (7). One or more spacers (332) may be positioned between the timber layers. The invention also related to timber composite (7) obtainable by such method and to decorative panels (1) comprising such timber composite (7) as a top layer.

BACKGROUND OF THE INVENTION

1. Field of the invention

Disclosed herein is a timber composite, a method of manufacturing atimber composite and decorative panels comprising such timber composite.In particular, the timber composite may be suitable for, but not limitedto, flooring or other surface applications.

2. Related Art

Composite timber is used as a construction and/or decorative material.However, known timber composite has low density and low strength, whichcan limit the viable applications for such timber.

Plywood is one example of a composite timber that is used as aconstruction material. To form plywood, several layers of wood (e.g.having a thickness of 1.6 mm to 2 mm) are stacked such that thedirection of the grains of the layers alternates. Adhesive is applied tothe surfaces of the layers of wood such that they are bonded to oneanother. The quality or veneer grade may change from high quality, orveneer grade A for the outermost layers or just for the top layer, tolow quality, or veneer grade C or less for the internal layers andpossibly the bottommost layer. Floor panels manufactured from suchplywood panels are disclosed in WO 2005/060507. In such floor panels theupper decorative surface is formed from a thick veneer of a high qualitygrade. The mechanical properties, such as impact and scratch resistance,of the upper surface depend on the wood species of this veneer.

For decorative reasons, some timber is produced with an embossed effect,where the surface of the timber is textured according to the grain ofthe timber. Such an effect is produced by scraping off portions of thesurface of the timber that are low density, either manually, e.g. with asteel brush, or by a machine. This results in the surface of the timberhaving a rugged “wire-drawn” or embossed appearance corresponding to thegrain of the timber. The timber used in such a process is low density,because only low density timber (e.g. pine, elm, oak, etc.) is suitablefor scraping. However, such timber, due to its low density, may beeasily damaged (e.g. forming a concave shape) or may wear quickly fromdaily usage, and thus may not be suitable for long term applications,e.g. in panels for a floor covering.

From WO 2010/032080 it is known to manufacture a wooden panel for use asa floor board by gluing and pressing scrap wooden strips. The obtainedfloor boards possess a high hardness. The resulting decorative aspect ofthe wood grain pattern is unnatural.

WO 2014/109697, which was not published at the earliest priority date ofthe present application, discloses a building panel comprising anMDF/HDF core with an applied thereon surface layer comprised of veneerand thermosetting resin. The building panel may amongst others be usedas a floor panel or a furniture panel. At the bottom of the panel abalancing layer of thermosetting resin is applied. The above referencesto the background art do not constitute an admission that the art formspart of the common general knowledge of a person of ordinary skill inthe art.

The above references are also not intended to limit the application ofthe methods or timber composite as disclosed herein.

SUMMARY OF THE DISCLOSURE

Disclosed herein is a method of manufacturing a timber composite, atimber composite and a decorative panel comprising such timbercomposite. The method comprises the steps of applying adhesive to one ormore timber layers, applying pressure to the one or more timber layers,and heating the timber layers, such that the adhesive penetrates intothe one or more timber layers and cures to form the timber composite.The application of pressure and heat is preferably done at least partlysimultaneously.

It is clear that when more than one timber layer is treated inaccordance with the invention, preferably a laminated assembly of thesetimber layers is attained, wherein the aforesaid adhesive not onlypenetrates the timber layers but also attaches adjacent superposedtimber layers to each other.

Preferably the adhesive is a thermosetting adhesive. Preferably theadhesive is based on melamineformaldehyde, ureumformaldehyde,melamine-ureumformaldehyde or phenolformaldehyde. According to variantssuch adhesives as polymeric MDI (Methylene Diphenyl di-Isocyanate) maybe used or other formaldehyde free adhesives, e.g. based on starch,proteins or carbohydrates such as sugar. Due to the use of athermosetting adhesive curing may be obtained in a heated pressoperation. In such case any compression obtained in the timber layersmay at least partially become permanent due to the adhesive curing inthe compressed state of the timber layers. It is however clear that somelimited amount of spring-back may occur upon release of the pressure.

The penetration of the adhesive into the timber layers differs, forexample, from plywood whereby the adhesive remains on the surface of theplywood layers. It has been found that, using a suitable adhesive, thenapplying an appropriate amount of heat and pressure to the timber layerscan allow the adhesive to penetrate into and throughout the fibers ofthe timber layers, Curing the resultant penetrated adhesive within thetimber layers can result in a denser and stronger composite timberproduct, e.g. as compared to the original timber layers.

The penetration of the adhesive into the one or more timber layers maybe such that it enters the available hollow spaces or voids in the woodstructure, such as vessels. Upon pressing and heating the hollow spacescollapse and their opposing walls are glued together permanently by thecured adhesive.

The method of the invention may lead to a permanent density increase ofthe thus treated one or more timber layers. The increase in density maybe due to several factors. One factor being an increase due to theweight of the impregnated adhesive and another factor being thecompression of the timber itself, for example because of the permanentcollapse of hollow spaces in the wood structure. Preferably a densityincrease of at least 20 percent is reached, and even better at least 50percent. For example a softwood species with a specific gravity of 0.47(at 12% moisture), e.g. Douglas-fir, may be upgraded by the method ofthe invention to a specific gravity of about 0.60.

An increase in density obtained with the method of the invention maylead to an increase of hardness of the treated one or more timberlayers.

In one embodiment the penetration of the adhesive may be such that it isdistributed generally evenly throughout the interstices and pores of thefibers of the one or more timber layers.

In one embodiment the adhesive may be applied to a plurality of timberlayers, and the method may further comprise arranging the plurality oftimber layers in a stack. This stack may then be fed in a heated press,for compressing and consolidating the plurality of timber layers.Preferably such stack exclusively comprises timber layers and adhesive.In accordance with a variant, such stack may comprise other layers aswell, such as reinforcement layers, for example glass fiber layers,either woven or non-woven. The incorporation of a glass fiber layer asan outermost layer or as an internal layer may lead to additional impactresistance, and may counteract a warping tendency of the resultingtimber composite. In accordance with another variant such stack maycomprise a board material, such as a chipboard or an MDF/HDF board, as alowermost layer or internal layer.

In one embodiment the method may further comprise the step of cuttingone or more timber pieces to form the plurality of timber layers.Preferably the plurality of timber layers comprised in one stack to bepressed is cut from the same piece of timber.

In one embodiment the timber layers may be arranged in the stack intheir original order in the timber piece from which they are cut suchthat a natural grain appearance of the timber piece is maintained. Thismay be desirable, for example, when the timber composite is to be usedfor decorative purposes, i.e. where the appearance of the grain isimportant to the use of the timber composite. The latter being the casein flooring or furniture applications. Whenever excessive wear leads tothe uppermost timber layer being worn out locally, the underlying timberlayer shows up at this spot with the same or very similar wood grain. Anaturally wearing surface is obtained.

In accordance with a variant of the above embodiment a timber compositemay comprise timber layers obtained from several timber pieces, whereinat one or both flat surfaces of the timber composite one or more timberlayers of a first, preferably high, quality are arranged, whilecentrally in the timber composite other, preferably lower quality timberlayers are arranged. Here below some possibilities are listed for thecombination of outer and inner timber layers, preferably respectivelyhigh and low quality timber layers.

According to a first possibility the outer or high quality timber layersconsist of timber layers of veneer grade A or better, and the inner orlow quality timber layers consists of timber layers of veneer gradequality lower than A, e.g. B or C.

According to a second possibility the outer or high quality timberlayers consist of timber layers of hardwood, while the inner or lowquality timber layers consist of timber layers of softwood. The hardwoodmay e.g. be oak, gumtree, birch or beech. The softwood may be pine.

According to a third possibility the outer or high quality timber layersconsist of timber layers with a specific gravity at 12% humidity of atleast 0.55 or of at least 0.5 ovendry weight, while the inner or lowquality timber layers consist of timber layers with a specific gravityof 0.5 or lower at 12% humidity, or of 0.45 or lower ovendry weight.

According to a fourth possibility the outer or high quality timberlayers consist of timber layers that are sliced or saw cut from thetimber piece, while the inner or low quality timber layers consists oftimber layers that have been rotary peeled from the timber piece.

According to a fifth possibility the outer timber layers consist ofstained timber layers, while the inner timber layers consists ofunstained timber layers.

According to a sixth possibility the outer timber layers consist oftimber layers with a thickness below 0.7 mm. Such thickness may ensuregood penetration of the adhesive and a resultant raise of the mechanicalproperties of interest, such as indentation resistance. The inner layersmay have any thickness, e.g. between 0.2 and 1 mm, even if the adhesivewould no longer be able to fully penetrate it.

According to a seventh possibility the outer timber layer, at least oneof the top and bottom layers, of the timber composite is penetrated witha melamine-based adhesive, while the central layers are penetrated withanother, preferably thermosetting, adhesive.

For the other adhesive use could be made of a phenol-based adhesive. Thelatter adhesive is more economic and possesses an excellent moistureresistance, but has the disadvantage that it is not transparent andhence colors the impregnated timber layers, while melamine istransparent. Preferably the top and/or bottom layers are free fromphenol adhesives, such as phenolformaldehyde.

Preferably at least two of the aforementioned high quality timber layersare present at at least one of the flat surfaces of the timbercomposite. In this way a naturally wearing surface can be obtained e.g.in flooring, to a satisfactory extent. The remainder of the timberlayers in the timber composite may then be of lower quality.

In one embodiment the cutting may be one of rotary peeling, slicing orsaw cutting. Preferably slicing or saw cutting is used, and mostpreferably saw cutting.

In one embodiment each timber layer may have a thickness of 0.2 mm to 1mm, wherein a thickness between 0.4 and 0.7 is preferred from the pointof view of penetration of the adhesive.

In one embodiment the timber may have a moisture content of 8% to 12%prior to the application of pressure and heat. The timber may be driedprior to performing the method in order to arrive at this moisturecontent.

In one embodiment the adhesive applied to the timber layers may be of atype that cures at high temperatures, e.g. at a temperature above 120°C. In this respect, preferably the adhesive does not cure until it hasfully penetrated the timber layers. Therefore, the adhesive preferablycomprises a flow and/or leveling agent such as polyglycolether,epsilon-caprolactam and butandiol.

In one embodiment the adhesive may be applied to one or both sides ofthe timber layer or of each timber layer. The adhesive may be a melamineresin or based on melamine resin, such as a melamine formaldehyde resin;and or a resin based on one or more of polyolefins, polyamides,polyurethane, polyvinyl acetal, urea, asphalt, etc. In the case theadhesive comprises melamine formaldehyde, such adhesive may comprise oneor more of the following properties:

-   -   the adhesive comprises a catalyst, such as NaOH and/or        thiosulphate, preferably in an amount of less than 20 parts per        100 parts melamine;    -   the adhesive comprises urea, preferably in an amount of less        than 20 parts per 100 parts of melamine;    -   the adhesive has a melamine to formaldehyde ratio of between 3:1        to 6:1, preferably about 5:1;    -   the adhesive comprises a plasticizer, such as polyvinyalcohol        and/or polyurethane.

In one embodiment the pressure applied to the timber may be between 2000kPa and 10,000 kPa.

In one embodiment the timber may be heated to a maximum temperature ofbetween 100° C. and 200° C.

Preferably the application of pressure and heat is at least partiallysimultaneously, such that the adhesive may cure to at least some extentunder pressure. In this way a compressed or densified state of the oneor more timber layers can at least partly be maintained permanently.

In one embodiment the timber may be gradually heated to allow theadhesive to fully penetrate the one or more timber layers. For example,in some cases when the timber is heated too quickly the adhesive maycure prior to fully penetrating the timber layers.

In one embodiment, when the step of heating the timber is performed, thetemperature of the timber may be increased from room temperature to amaximum temperature (e.g. being in the range of 50° C. to 100° C.)gradually over a period of 20 to 60 minutes. Again, the gradual increasein temperature may allow the adhesive to fully penetrate and/or bedistributed generally evenly throughout the one or more timber layers,thereby penetrating the interstices and pores of the fibers.

In one embodiment the method may further comprise the steps of coolingthe timber and releasing the pressure. In one embodiment the pressuremay only be released once the temperature of the timber has returned toapproximately room temperature. Delaying the release of the pressure maybetter allow the adhesive to fully cure.

In one embodiment the method may further comprise the step ofpositioning a spacer between two timber layers. When a spacer is locatedbetween two timber layers, it may help to reduce or inhibit the escapeof moisture from the timber layers. When moisture is trapped in thetimber, the timber may soften, which in turn facilitates compression ofthe timber. It may also provide varying compression or shrinkage of thespring wood and summer wood in the timber. When the adhesive cures itmay hold the timber in this shape such that the resulting timbercomposite has raised portions of summer wood, i.e. such that the textureof the grain structure is enhanced.

In one embodiment the adhesive may be applied to a plurality of timberlayers. The spacer may be positioned such that a stack of timber layersis formed on either side of the spacer. Each stack of layers may be cutfrom a different timber piece.

In one embodiment each stack of layers on either side of the spacer maybe arranged in the original order from which they are produced from thetimber piece(s), such that a natural grain of each stack may bemaintained. This may be desirable in decorative applications where thetimber composite will be visibly used (e.g. flooring). Preferably notonly the original order, but also the original mutual orientation of thetimber layers is maintained. It is of course possible that two timberlayers that are adjacent in a stack were not positioned adjacently inthe original timber piece, but were rather separated by an intermediatetimber layer that is missing in the stack, e.g. because this timberlayer was wasted during the manufacturing.

In one embodiment the spacer may be a sheet of cardboard, plastic orsoft metal.

In one embodiment the method may further comprise the step of applying astain to the one or more timber layers, preferably prior to applying anadhesive to the one or more timber layers. The stain may be applied soas to penetrate into and be distributed evenly within the one or moretimber layers. In accordance with a variant the stain may be applied atthe same time as the application of the adhesive. The stain may be mixedinto the adhesive before application thereof, or the stain may beapplied to a surface of the timber layer immediately before or after theapplication of the adhesive.

When the timber layers are, for example, thinly cut the stain may moreeasily penetrate into and be evenly distributed throughout each timberlayer, including into pores and interstices between fibers (e.g.compared to a block or panel of timber). In this way, when the timberlayers are formed into a timber composite, the timber composite has acoloring, preferably an even coloring, (i.e. stain) throughout itsinterior. This even coloring (or staining) throughout the timbercomposite may not be achievable, or may be difficult to achieve, with atraditional block or panel of timber where the stain can only be appliedto the outer surface of the block of timber, in which case the stain maynot or not fully penetrate into its interior.

An even distribution of stain or a distribution of stain throughout thetimber composite may be desirable, for example, when the timbercomposite is used in applications in which it may be subject to wear.Without a uniform distribution of stain or without a sufficiently deepdistribution of stain (i.e. when stain does not penetrate into thetimber), wearing of the surface of the timber will cause the color ofthe timber to fade (i.e. because the areas that are more deeply stainedon the surface are worn away). On the other hand, by staining the layersof timber composite such that the stain is distributed throughout thetimber, preferably generally uniformly, removal of the surface of thetimber composite (e.g. through wear) may not affect the appearance ofthe timber composite.

Also disclosed herein is a method of manufacturing a timber composite.The method comprises the steps of applying adhesive to a plurality oftimber layers, arranging the timber layers in a stack, and positioning aspacer between two of the timber layers in the stack. The method furthercomprises applying pressure to the stack of timber layers and heatingthe stack of timber layers, such that the adhesive penetrates into thetimber layers and cures to form the timber composite.

The method may be as otherwise defined above.

Also disclosed herein is a timber composite manufactured using themethods as defined above.

Further disclosed herein is a timber composite, which independently fromthe method in which it is manufactured, comprises at least two timberlayers penetrated with a cured adhesive, wherein said cured adhesivealso connects said two timber layers. In accordance with preferredembodiments of such timber composite, it may show the preferred featuresof the timber composite disclosed before, irrespective of the way it hasbeen manufactured. Some important preferred features are listed herebelow and may be present in isolation or in combination within one andthe same timber composite, namely:

-   -   the preferred feature that said two timber layers have a        thickness below 1.5 mm, and preferably above 0.1 mm;    -   the preferred feature that said two timber layers have a        thickness below 1 mm and preferably above 0.2 mm;    -   the preferred feature that at least one of said two timber        layers is stained, and preferably both timber layers are        stained;    -   the preferred feature that said cured adhesive is a        thermosetting adhesive comprising at least one constituent        chosen from the list consisting of melamineformaldehyde,        ureumformaldehyde, melamine-ureumformaldehyde and        phenolformaldehyde;    -   the preferred feature that said two timber layers are cut from        one and the same piece of timber, and preferably are present in        said timber composite in their original mutual order and/or        mutual orientation;    -   the preferred feature that said timber composite has an        increased density as compared to the original timber layers,        wherein said increase is at least 20 percent, and even better at        least 50 percent;    -   the preferred feature that said timber layers consist of timber        layers of hardwood;    -   the preferred feature that said timber layers consist of timber        layers having a specific gravity at 12% moisture content of at        least 0.55;    -   the preferred feature that said timber composite comprises outer        and inner timber layers in accordance with one or more of the        above described seven possibilities for combining inner and        outer timber layers of differing nature or quality;    -   the preferred feature that said timber composite has a structure        of raised summer wood grain, while the spring wood is depressed;    -   the preferred feature that said timber layers are compressed        such that their structure is free from voids.

Also disclosed herein is a timber composite comprising timber layers andan adhesive matrix. At least one surface of the timber composite hasraised portions of summer wood and depressed portions of spring wood.

The invention further relates to a decorative panel comprising asubstrate material and a decorative top layer, with as a characteristicthat said top layer is formed by a timber composite comprising at leastone timber layer penetrated with a cured adhesive.

Preferably two or more superposed timber layers are comprised in saidtop layer, wherein said cured adhesive connects adjacent timber layersin said top layer. It is clear that the timber composite productsdescribed above, whether or not obtained with the aforementioned methodof the invention may be used as said top layer.

In a preferred embodiment of said decorative panel, said substratematerial is a wood-based material, chosen from the list consisting of aMDF or HDF board, a chipboard, a

Wood Plastic Composite board, a so-called lamella core, namely a boardassembled from laths of e.g spruce or hevea, a thermoplastic board and aplywood board.

Preferably said decorative panel is a floor panel. It is clear that theapplication of a timber composite as described above in a floor panelcreates large advantages. The looks of the floor panel are those ofgenuine parquet, while the mechanical properties of the surface areunequalled and comparable to those of laminate flooring. The decorativepanel of the invention may avoid the need for sanding, even in the casethe timber layers are stained.

The use of a timber composite to form the decorative surface of a floorpanel, or other decorative panels, may obviate the need for finishingsuch panels with wear resistant coatings such as UV lacquers or oils.

Preferably said floor panel is of the type that is suitable for afloating installation.

Preferably, the decorative panel is a square or rectangular floor panelwhich, on at least one pair of opposite edges, and preferably at bothpairs, is provided with mechanical coupling allowing to couple two ofsuch floor panels to each other in such a manner that a locking iscreated in a vertical direction perpendicular to the plane of thecoupled panels, as well as in a horizontal direction perpendicular tothe coupled edge and in the plane of the panels.

Preferably, the coupling also shows one or a combination of two or moreof the following features:

-   -   the feature that the mechanical coupling or coupling parts are        substantially realized as a tongue and a groove bordered by an        upper lip and a lower lip, wherein this tongue and groove        substantially are responsible for the locking in said vertical        direction, and wherein the tongue and the groove are provided        with additional locking parts, substantially responsible for the        locking in said horizontal direction. Preferably, the locking        parts comprise a protrusion on the lower side of the tongue and        a recess in the lowermost groove lip. Such coupling and locking        parts are known, for example, from WO 97/47834; preferably the        coupling, or at least said tongue and groove are realized in the        substrate material;    -   the feature that the mechanical coupling or coupling parts press        the coupled floor panels against each other, for example, in        that these mechanical coupling approaches are provided with a        so-called pre-tension, as known as such from EP 1 026 341. The        tensioning force with which the floor panels are pressed against        each other or towards each other, can be obtained, for example,        in combination with the above feature by a lower lip, which is        bent out in coupled position and which, when trying to spring        back, presses against the lower side of the tongue;    -   the feature that the mechanical coupling allow a coupling by a        horizontal, or quasi-horizontal shifting movement of the panels        towards each other;    -   the feature that the mechanical coupling allows a coupling by a        turning movement W along the respective edges;    -   the feature that the mechanical coupling allows a coupling by a        downward-directed movement of a male coupling part having, for        example, a tongue, up into a female coupling part having, for        example, a groove;    -   the feature that the mechanical coupling, or at least the        pertaining upper edge, is realized by a milling operation with        rotating milling tools;    -   the feature that the mechanical coupling is for the major part        realized in said substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described by way of example only, with referenceto the accompanying drawings in which:

FIG. 1 is a flow chart illustrating a method of manufacturing a timbercomposite;

FIG. 2 schematically illustrates an apparatus for manufacturing a timbercomposite;

FIG. 3 is a flow chart illustrating a further method of manufacturing atimber composite;

FIG. 4 schematically illustrates a further apparatus for manufacturing atimber composite;

FIG. 5 shows a perspective view of a decorative panel in accordance withthe invention;

FIGS. 6 and 7 are cross-sections at a larger scale according to the lineVI-VI and VII-VII respectively in FIG. 5;

FIG. 8 in a view similar to that of FIG. 7 illustrates a variant;

FIG. 9 illustrates how the floor panel of FIG. 8 may be joint to form afloating floor covering; and

FIG. 10 at a larger scale illustrates the area indicated with F10 onFIG. 6.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

In the following detailed description, reference is made to accompanyingdrawings which form a part of the detailed description. The illustrativeembodiments described in the detailed description, depicted in thedrawings and defined in the claims, are not intended to be limiting.Other embodiments may be utilized and other changes may be made withoutdeparting from the spirit or scope of the subject matter presented. Itwill be readily understood that the aspects of the present disclosure,as generally described herein and illustrated in the drawings can bearranged, substituted, combined, separated and designed in a widevariety of different configurations, all of which are contemplated inthis disclosure.

Referring firstly to FIG. 1, the method 110 comprises rotary cutting orslicing a timber billet into timber layers 112. Natural timber can warpdue to differential shrinkage of the wood as it dries. This differentialshrinkage causes internal stresses (i.e. due to tension) in the timber.When the timber is cut into thin layers, these stresses are reduced. Inthis case the timber layers have a thickness of 0.01-1.5 mm. After thetimber is cut, the timber layers are in a natural state containingwater. The water content of the timber layers can be reduced to 1%-20%by natural drying or machine drying, which can result in the producedtimber composite (discussed in more detail below) having a higherdensity.

After the timber is cut into timber layers 112, a stain is applied toeach layer 114. Applying the stain 114 to the thin layers of timbermeans that it more easily penetrates into and throughout the timber. Inthis way, the stain may be generally distributed throughout the timber.Thus, when, the timber layers are later formed into a composite timber(discussed below) the stain may be evenly distributed throughout thetimber. This may not be the case with, for example, a block or panel oftimber where the stain is applied to the external surface, because thestain may not be able to penetrate into the center of the block or panelof timber (this may especially be the case with hardwoods).

The method 110 further comprises applying an adhesive 116, of the typethat cures at high temperatures, to the surfaces of the timber layers.The adhesive is applied by spray gun to a single surface of each of thetimber layers. The adhesive may contain formaldehyde, sodium hydroxide,urea, melamine, polyvinyl alcohol, polyolefine, polyamide adhesive,polyurethane and/or asphalt.

In the illustrated embodiment the adhesive is prepared by mixing evenly10 parts by weight of formaldehyde, 5 parts by weight of sodiumhydroxide, 5 parts by weight of urea, 50 parts by weight of melamine, 5parts by weight of polyvinyl alcohol, 5 parts by weight of polyolefine,5 parts by weight of polyamide adhesive, 5 parts by weight ofpolyurethane, and 10 parts by weight of asphalt in a reaction vessel ata temperature of 80 degrees centigrade. It would be understood by aperson skilled in the art that the amounts of each component and thereaction temperature can be varied without departing from the scope ofthe invention.

The method 110 further comprises arranging the timber layers in a stack118. The layers are arranged so as to be in their original order in thetimber billet, which ensures that the wood grain of one layer matchesthe grain of its adjacent layers (such that the stack retains theappearance of the original timber billet).

The method 110 further comprises applying a pressure of 0.1-30 MPa tothe stack of timber layers 120 and heating the stack 122 to atemperature between 50° C. and 250° C. and typically 100° C. to 200° C.The stack is gradually heated from room temperature to this temperatureover a period of between 3 minutes and 20 minutes. In other embodiments,the temperature may be increased at a faster or slower rate (i.e. over ashorter or longer period of time).

The heat 122 and pressure 120 causes the adhesive to penetrate into andthroughout the fibers of the timber layers including into theinterstices and pores between fibers. The gradual heating of theadhesive provides the adhesive with time to penetrate into the timber.Once the adhesive cures it holds the timber in shape (i.e. the shape ittakes when compressed or pressurized), such that upon release of thepressure it does not return (e.g. bounce back) to its original shape.Thus, the density of the timber composite is higher than the density ofthe original timber billet (i.e. the non-composite timber). The timberlayers are bonded to one another by the curing of the adhesive and forma single piece of high density composite timber. The timber is thenallowed to cool and the pressure is released.

FIG. 2 schematically illustrates an apparatus 224 used to manufacture acomposite wood board, for example, according to the method shown in FIG.1 and described above.

As illustrated, four sheets of timber 226 are stacked on top of oneanother to form a stack of timber layers 228. Each timber layer 226 hasbeen coated with adhesive by way of spray gun, and has a thickness of1.5 mm and a water content of 1%. The stack of timber layers 228 ispositioned between two steel plates 230 which, in use, apply a pressureof 1-20 MPa to the stack of timber layers 228. Additionally, each steelplate 230 can be gradually heated from room temperature to 100-200° C.over a period of 3-20 minutes, which in turn heats the stack of timberlayers 228. The heat can be transferred directly from the steel plates230 to the stack of timber layers 228. This allows the adhesive topenetrate the fibers of the timber and cure, so as to bond the timberlayers 226 to one another. The bonding of the timber layers 226 forms ahigh density composite timber. The pressure applied by the steel plates230 is then released and the timber composite is allowed to cool.Referring now to FIG. 3 the method 310 is similar to that shown in FIG.1 and described above, but includes some differences. For example, themethod 310 further comprises the step of positioning a spacer 332between two timber layers in the stack. The spacer may be a sheet ofcardboard, plastic or soft metal. As set forth above, when the stack oftimber layers is pressurized (i.e. compressed) 320 and heated 322, theadhesive permeates (or penetrates) into the fibers of the timber andcures. Additionally, the moisture in the timber tends to move towardsthe center of the stack of timber layers (due to heat being transferredat external surfaces of the stack). When a spacer is positioned betweentwo of the layers it prevents passage of moisture between the layers(i.e. the moisture is essentially trapped by the spacer). As thetemperature increase 322 the moisture forms steam, which softens thetimber layers located either side of the spacer. The spring wood in thetimber layers shrinks to a greater extent than the summer wood in thetimber layers. When the adhesive cures (as discussed above), itgenerally holds the timber in its compressed shape, with the spring woodhaving shrunk to a greater extent than the summer wood. Upon release ofthe pressure, the timber generally does not return, e.g. bounce back, toits original shape. The summer wood however, due to its greater density,may minimally return to its natural state, whilst the spring wood in thetimber does not return (e.g. bounce back). Hence, the resultant timberhas raised portions of summer wood and depressed portions of springwood. This produces an embossed appearance that accentuates the grainstructure of the timber. Due to the depth of the grain, this embossed,wood grain, appearance can remain even after polishing the timbercomposite.

When the timber layers are cut 312 from a single piece of timber (e.g.billet—as is the case in this embodiment), the timber layers can bestacked 318 in the same order and orientation as they were in before thebillet was cut (i.e. so as to essentially re-form the original piece oftimber). By doing so, the produced timber composite will have the same(or similar) natural wood grain of the original timber piece and havinga wire-drawing and embossed effect.

FIG. 4 schematically illustrates an apparatus 424 for simultaneouslypressing multiple composite timber boards 426 according to, for example,the method 310 shown in FIG. 3 and described above.

Two stacks 428 of timber layers 426, each consisting of timber layers426 of 1.2 mm thickness, are positioned adjacent to one another (i.e.one on top of the other). A spacer in the form of a plastic sheet 434 ispositioned between the adjacent stacks of timber layers 428. In theillustrated embodiment each timber layer 426 has a water content of 20%.The apparatus 424 comprises two steel plates 430, which the stacks oftimber layers 428 are positioned between. The steel plates 430 arecapable of applying pressure of 1-20 MPa to the stacked wood sliceassemblies 428. Whilst not shown, the apparatus 424 comprises a heateralso capable of directly heating the two steel plates to 100-200° C.,over a period of 3-20 minutes. In use, this heat is transferred from thesteel plates 430 to the timber layers 426. Two or more composite timberboards are produced after the release of the pressure and then theremoval of the plastic sheet spacer 434. In this respect, the apparatus424 allows more than one composite timber board to be produced in onepressing and heating operation. Thus apparatus 424 may provide anefficient way to produce multiple timber composite boards, which may inturn provide energy savings. Further, and as set forth above withregards to the method 310 shown in FIG. 3, the apparatus 424 may allowthe production or manufacture of timber composite having an embossed(i.e. raised grain) appearance.

In the illustrated embodiment, two stacks of timber layers 428 areshown, each having four timber layers 426. In alternative embodiments,there may be three, four, five, etc. stacks of timber layers (havingspacers therebetween) each having one, two, three, five, six, etc.timber layers. In such embodiments, any timber composite produced fromstacks located between two spacers would have an embossed appearance onboth (e.g. upper and lower) sides. It would be understood by a personskilled in the art that the number and the thickness of the timberlayers in each stack of timber layers can be varied to vary qualities ofthe timber composite that is produced by the apparatus.

FIG. 5 illustrates a decorative panel, more particularly a floor panel1, in accordance with the invention. The panel 1 is rectangular andoblong and comprises a pair of opposite short edges 2-3 and a pair ofopposite long edges 4-5. The decorative upper surface 6 is formed by atimber composite 7.

FIG. 6 clearly shows that the decorative panel 1 comprises a substratematerial 8 upon which the timber composite 7 is provided, e.g. glued orotherwise connected. The substrate material 8 in this case consists of aso-called lamella core, which comprises a plurality of adjacent laths 9oriented cross wise over the length of the floor panel 1. Preferablysuch laths are made from softwood, e.g. spruce or hevea. The outermostlaths 9A-9B that form the short edges 2-3 may be made from a differentmaterial, such as from MDF/HDF or plywood. Such material allows for abetter processing, for e.g. milling to form the mechanical couplingparts 10 therein. At the bottom of the substrate material 8 a backinglayer 11 is provided, e.g. glued or otherwise attached against thelamella core. Such backing layers is preferably made from a wood veneerhaving a thickness of at least 50 percent of said timber composite 7forming the upper surface 6. According to a variant a timber composite 7may be used for the backing layer 11 as well.

FIGS. 6 and 7 illustrate that both pairs of opposite edges 2-3-4-5 areprovided with mechanical coupling 10 that is substantially realized as atongue 12 and a groove 13 bordered by an upper lip 14 and a lower lip15, wherein this tongue 12 and groove 13 substantially are responsiblefor the locking in a vertical direction V, and wherein the tongue 12 andthe groove 13 are provided with additional locking parts 16-17,substantially responsible for the locking in a horizontal direction H.Preferably, the locking parts comprise a protrusion 16 on the lower sideof the tongue 12 and a recess 17 in the lowermost groove lip 15. Thecoupling parts 10 illustrated in FIGS. 6 and 7 at least allow a couplingby a turning movement W along the respective edges 2-3-4-5 and/or acoupling by a shifting movement S in a substantially horizontal fashionof the edges 2-3-4-5 to be coupled towards each other.

FIGS. 8 and 9 illustrate a variant with a short pair of edges 2-3 thatallow a coupling at least by a downward-directed movement D. One edge 2is provided with a male coupling part 18, while the other edge 3 of thisshort pair 2-3 is provided with a female coupling part 19. By thedownward movement D the male coupling part 18 is pushed into the femalecoupling part 19 to become locked in the vertical direction V due to apair of cooperating heels 20 and recesses 21. In this case the recess 21is partly formed by a resilient element 22 arranged in the femalecoupling part 19.

FIG. 10 gives a detailed view on the composite structure of the timbercomposite 7 that forms the upper decorative surface 6. The timbercomposite 7 is formed by a plurality of superposed timber layers 23 thatare penetrated with cured adhesive 24. Further the timber composite 7shows an embossed effect at the decorative upper surface 6, wherein thesummer wood 25 shows up as a raised portion 26. FIG. 10 clearlyillustrates that the plurality of timber layers 23 have been assembledor laminated on top of each other such that the summer wood 25 of theplurality of timber layers is substantially vertically aligned. Theorder and orientation of the timber layers 23 has been maintained ascompared to the order in which they were cut from a timber billet.

Some embodiments of the invention have been described above, but theinvention may be embodied in many other forms. Modifications andimprovements can be made by a person skilled in the art withoutdeparting from the essence of the present invention. Such modificationsand improvements fall within the scope of the present invention.

For example, the spacer can alternatively be paper or card board,plastic film, soft metal (e.g., aluminum or copper) etc. Alternatively,the spacer may be formed from a combination of these materials.

Further, the timber layer may have a thickness of 0.01 to 100 mm.Alternatively, the timber layer may have a thickness between 0.1 to 5 mmor 1 to 3 mm. In case the timber composite is used as the top layer in adecorative flooring panel, the thickness is preferably at least about2.5 mm and may range up to 3.5 or 4 mm. To reach such thickness it isclear that the timber composite should preferably comprise two or moretimber layers. It is not excluded that a timber composite forming theupper surface of the decorative flooring panel would only comprise onetimber layer penetrated with cured adhesive. Such floor panel presentsimportant advantages over floor panels for veneer parquet.

The timber composite produced from the methods and apparatus set forthabove may have a higher density if the thickness of the wood slices isalternatively between 0.2 to 1 mm. Additionally, the cutting method canbe rotary peel, slicing or saw cutting.

The moisture content of the timber layers may be 1% to 60%.Alternatively the moisture content may be 5% to 30%. Alternatively themoisture content may be 8% to 12%.

The pressure applied to the timber layers or stacks may be 0.01 MPa to30 MPa. Alternatively the pressure may be 0.05 MPa to 20 MPa.Alternatively the pressure may be 2 MPa to 10 MPa.

The maximum temperature applied to the timber layers or stacks may be10° C. to 400° C. Alternatively the temperature may be 50° C. to 300° C.Alternatively the temperature may be 100° C. to 200° C.

As discussed above, the number of timber layers in each stack can bevaried as needed. For example, there may be one, two, three, four, five,etc. layers in each stack of timber layers. Additionally, each stack oftimber layers does not have to have the same number of timber layers asother stacks.

Multiple spacers can be used between stacks of timber layers. Forexample, when there are three stacks of timber layers, two spacers maybe positioned between the stacks.

The surfaces of the timber layers can be coated with adhesive by, forexample, using one or more of the following methods:

-   -   1. The adhesive can be sprayed to a surface of a timber layer by        using a spray gun so that the adhesive can be applied to the        surface of the timber layer evenly.    -   2. The adhesive can be applied to a surface of a timber layer by        using a coating roller, so that the adhesive can be applied to        the surface of the timber layer evenly.    -   3. The timber layer can be dipped into adhesive so that the        fibers in the timber layer can naturally absorb the adhesive,        thus coating the surface of the timber layer with adhesive.    -   4. Providing the adhesive in a sealable container, dipping a        timber layer into the adhesive, sealing the container,        pressurizing the interior of the container. This may force the        adhesive to permeate into the wood fibers of the timber layer        more sufficiently under pressure.    -   5. Applying adhesive to both sides of a carrier, and placing the        carrier between two wood slices so that the adhesive can        permeate into the wood fibers of the wood slices 1 sufficiently.        The carrier can be, for example, paper or nonwoven cloth.

EXAMPLES Example 1

Six timber layers of 0.6 mm thickness were sliced from a timber billet.The timber layers were kiln dried in order to reduce their moisturecontent to approximately 10%. Adhesive was then sprayed on to both sidesof the timber layers. Following this, the timber layers were again kilndried to a moisture content of approximately 10%.

The six timber layers were then arranged in a stack according to theorder they were sliced from the timber billet. This stack was placedinto a pressing machine, which was used to apply 7 MPa of pressure tothe stack. The temperature was increased from 20° C. to 200° C. over a60 minute period and then held at 200° C. for 20 minutes. Followingthis, the temperature was decreased from 200° C. to 20° C. over a periodof 45 minutes.

The pressure was then released from the stack of timber layers, whichwere formed into a timber composite board having smooth upper and lowersurfaces.

Example 2

Twelve timber layers of 0.6 mm thickness were sliced from a timberbillet. The timber layers were kiln dried in order to reduce theirmoisture content to approximately 10%. Adhesive was then sprayed on toboth sides of the timber layers. Following this, the timber layers wereagain kiln dried to a moisture content of approximately 10%.

The twelve timber layers were then arranged in two stacks, each stackhaving six timber layers stacked according to the order they were slicedfrom the timber billet. The stacks were placed into a pressing machineand a plastic film spacer was placed between the two stacks of timberlayers. Using the press, a pressure of 7 MPa was applied to the stacks.The temperature was increased from 20° C. to 200° C. over a 60 minuteperiod, and then held at 200° C. for 20 minutes. Following this, thetemperature was reduced from 200° C. to 20° C. over a period of 45minutes.

The pressure was then released from the stacks of timber layers and theplastic film was removed. Each stack was formed into a timber compositeboard having one surface with a raised grain or embossed appearance.

Example 3

The timber was sliced into a series of 0.5 mm thick veneer. The veneerwas dried so as to reduce the veneer moisture content to 12% by weight.

Formaldehyde melamine adhesive (200 g/m²) was sprayed onto the veneer,then the veneer was dried again to a moisture content of 12% by weight.

The veneer was then stacked according to the original order of slicing.

Pressure (95 kg/cm²) then heat ware applied to the stack. Thetemperature was raised from room temperature to 180° C. When theadhesive in the stack was fully cured, the temperature was reduced backto room temperature.

Example 4

The timber was sliced into a series of 0.5 mm thick veneer. The veneerwas dried so as to reduce the veneer moisture content to 12% by weight.

Formaldehyde melamine adhesive (200 g/m²) was sprayed onto the veneer,then the veneer was dried again to a moisture content of 12% by weight.

The veneer was then stacked in two separate stacks according theoriginal order of slicing. The two stacks were separated by a plasticfilm. Use of plastic film allowed an embossed look to be achieved.

Pressure (95 kg/cm²), then heat, were applied to the stack. Thetemperature was raised from room temperature to 180° C. When theadhesive in the stack was fully cured, the temperature was reduced backto room temperature.

In the claims which follow, and in the preceding description, exceptwhere the context requires otherwise due to express language ornecessary implication, the word “comprise” and variations such as“comprises” or “comprising” are used in an inclusive sense, i.e. tospecify the presence of the stated features but not to preclude thepresence or addition of further features in various embodiments of themethods or timber composite as disclosed herein.

The invention claimed is:
 1. A method of manufacturing a timbercomposite, the method comprising the steps of: cutting one or moretimber pieces to form a plurality of timber layers; applying adhesive tothe plurality of timber layers; arranging the plurality of timer layersin a stack; applying pressure to the timber layers; and heating thetimber layers, such that the adhesive penetrates into the one or moretimber layers and cures to form the timber composite, wherein the timberlayers are arranged in the stack in their original order and orientationin the timber piece from which they are cut, and wherein the adhesive isa thermosetting adhesive.
 2. The method of claim 1, wherein the adhesivepenetrates such that it is distributed generally evenly throughout theone or more timber layers.
 3. The method of claim 1, wherein the cuttingis one of rotary peeling, slicing or saw cutting.
 4. The method of claim1, wherein each timber layer has a thickness of 0.2 mm to 1 mm.
 5. Themethod of claim 1, wherein the timber has a moisture content of 8% to12% prior to the application of pressure and heat.
 6. The method ofclaim 1, wherein the adhesive is based on melamineformaldehyde,ureumformaldehyde, meamine-ureumformaldehyde or phenolformaldehyde. 7.The method of claim 1, wherein the adhesive is applied to one or bothsides of or each timber layer.
 8. The method of claim 1, wherein thepressure applied to the timber is between 0.1 MPa and 30 MPa.
 9. Themethod of claim 1, wherein the timber is heated to a maximum temperatureof between 50° C. and 250° C.
 10. The method of claim 1, wherein thetimber is gradually heated to allow the adhesive to fully penetrate theone or more timber layers.
 11. The method of claim 1, wherein, when thestep of heating the timber is performed, the temperature of the timberis increased from room temperature to a maximum temperature graduallyover a period of 20 to 60 minutes.
 12. The method of claim 1, furthercomprising the steps of cooling the timber and releasing the pressure,wherein the pressure is only released once the temperature of the timberhas returned to approximately room temperature.
 13. The method of claim1, further comprising the step of positioning a spacer between twotimber layers.
 14. The method of claim 13, wherein the adhesive isapplied to a plurality of timber layers, the spacer positioned such thata stack of timber layers is formed on either side of the spacer.
 15. Themethod of claim 14, wherein each stack of layers is cut from a differenttimber piece.
 16. The method of claim 14 wherein each stack of layers oneither side of the spacer is arranged in the original order from whichthey are produced from the timber piece(s), such that a natural grain ofeach stack is maintained.
 17. The method of claim 13, wherein the spaceris a sheet of cardboard, plastic or soft metal.
 18. The method of claim1, further comprising the step of applying a stain to the one or moretimber layers prior to applying an adhesive to the one or more timberlayers.
 19. The method of claim 18, wherein the stain is applied so asto penetrate into and be distributed evenly throughout the one or moretimber layers.
 20. A timber composite comprising timber layers and anadhesive matrix, at least one surface of the timber composite havingraised portions of summer wood and depressed portions of spring wood.21. A decorative panel comprising a substrate material and a decorativetop layer, wherein the top layer is formed by a timber compositecomprising a plurality of timber layers obtained from a same timberpiece and penetrated with a cured thermosetting adhesive, wherein saidtimber layers are available in said top layer in their original order inwhich they were cut from said timber piece.
 22. The decorative panel ofclaim 21, wherein for said timber composite use is made of a timbercomposite in accordance with claim
 20. 23. The method of claim 1,wherein the adhesive contains formaldehyde, sodium hydroxide, urea,melamine, polyvinyl alcohol, polyolefine, polyamide adhesive,polyurethane or asphalt.
 24. The method of claim 1, wherein a highdensity timber composite is obtained in that the density of the timbercomposite is increased compared to the timber pieces or timber layers.25. The method of claim 8, wherein the pressure applied to the timber isbetween 2 MPa and 10 MPa.
 26. The method of claim 9, wherein the timberis heated to a maximum temperature of between 100° C. and 200° C.